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41.
42.
Several researchers have proposed solutions to control type I error rate in sequential designs. The use of Bayesian sequential design becomes more common; however, these designs are subject to inflation of the type I error rate. We propose a Bayesian sequential design for binary outcome using an alpha‐spending function to control the overall type I error rate. Algorithms are presented for calculating critical values and power for the proposed designs. We also propose a new stopping rule for futility. Sensitivity analysis is implemented for assessing the effects of varying the parameters of the prior distribution and maximum total sample size on critical values. Alpha‐spending functions are compared using power and actual sample size through simulations. Further simulations show that, when total sample size is fixed, the proposed design has greater power than the traditional Bayesian sequential design, which sets equal stopping bounds at all interim analyses. We also find that the proposed design with the new stopping for futility rule results in greater power and can stop earlier with a smaller actual sample size, compared with the traditional stopping rule for futility when all other conditions are held constant. Finally, we apply the proposed method to a real data set and compare the results with traditional designs. 相似文献
43.
张丽娜 《佳木斯大学社会科学学报》2009,27(4):148-149
非言语交际作为言语交际的重要组成部分,在外语教学中,起着不可忽视的作用。恰当地使用非言语交际行为,能够创建良好的师生关系,提高学生学习兴趣。本文分析了非言语交际行为的重要性及其在外语课堂教学中的表现形式和作用。 相似文献
44.
我国新型农民合作社的形态、功能及其发展 总被引:4,自引:0,他引:4
按照性质不同,我国的农民合作社可划分为新型农民合作社和传统农民合作社两大类型.新型农民合作社的基本功能是农户间的团结协作和互利互惠,它有利于促进农业产业化经营;抵御农业经营风险;实现农民共同富裕;推进农村民主政治建设.从我国的情况看,在发达国家农业产业化经营的三种模式--综合型模式、合同型模式和合作社型模式中,合作社型模式更适合我国的农业产业化经营.由于当前在发展新型农民合作社中存在的,诸如合作的认识不够明确、合作的环境不够优良、合作的机制不够完善的问题,这需要通过教育普及国际公认的合作经济理论和实务知识;尽快出台<农村资金合作社法>,明确各类农民合作社的主管部门;建立、健全合作社"三会"制度及议事规则. 相似文献
45.
Plotting of log−log survival functions against time for different categories or combinations of categories of covariates is perhaps the easiest and most commonly used graphical tool for checking proportional hazards (PH) assumption. One problem in the utilization of the technique is that the covariates need to be categorical or made categorical through appropriate grouping of the continuous covariates. Subjectivity in the decision making on the basis of eye-judgment of the plots and frequent inconclusiveness arising in situations where the number of categories and/or covariates gets larger are among other limitations of this technique. This paper proposes a non-graphical (numerical) test of the PH assumption that makes use of log−log survival function. The test enables checking proportionality for categorical as well as continuous covariates and overcomes the other limitations of the graphical method. Observed power and size of the test are compared to some other tests of its kind through simulation experiments. Simulations demonstrate that the proposed test is more powerful than some of the most sensitive tests in the literature in a wide range of survival situations. An example of the test is given using the widely used gastric cancer data. 相似文献
46.
Two-step estimation for inhomogeneous spatial point processes 总被引:1,自引:0,他引:1
Rasmus Waagepetersen Yongtao Guan 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2009,71(3):685-702
Summary. The paper is concerned with parameter estimation for inhomogeneous spatial point processes with a regression model for the intensity function and tractable second-order properties ( K -function). Regression parameters are estimated by using a Poisson likelihood score estimating function and in the second step minimum contrast estimation is applied for the residual clustering parameters. Asymptotic normality of parameter estimates is established under certain mixing conditions and we exemplify how the results may be applied in ecological studies of rainforests. 相似文献
47.
靳开宇 《重庆邮电大学学报(社会科学版)》2017,29(3):71-75
在网络言语交际过程中,网络语言娱乐性的表现形式、特点及其制约机制等问题一直是学界关注的话题.为从语言功能视角阐释网络语言娱乐性的实现方式及其根源等问题,运用了比较分析和例证相结合的研究方法,通过比较分析说明网络语言的内涵及其存在形式的双重性特征,介绍了语言娱乐功能的内涵和陈望道先生的“辞趣”思想,通过网络语言在形趣、音趣和意趣方面的例证分析,对“辞趣”理论实质从语言娱乐功能实现角度重新进行了梳理,指出网络语言娱乐功能具体实现的语言结构形式途径,认为网络言语交际中娱乐性的根源来自于社会物质条件和主体内在需求的合力,因为使用了网络媒介,所以才表现出独具特色的网络言语交际形式. 相似文献
48.
In this exploratory study, we examine whether organizational mission statement attributes make a difference to the performance of nonprofit performing arts organizations. We use text analysis to measure two semantic attributes—activity and commonality—of mission statements. We examine whether these attributes are associated with improved performance for the instrumental and expressive functions of nonprofit performing arts organizations. Our findings indicate that the mission statement attribute activity is associated with improved performance for both instrumental and expressive functions. Our analysis of nonfindings for the mission statement attribute commonality suggests that there is a need to develop and use content analysis tools tailored to nonprofit contexts. 相似文献
49.
In this paper, we consider a generalisation of the backward simulation method of Duch et al. [New approaches to operational risk modeling. IBM J Res Develop. 2014;58:1–9] to build bivariate Poisson processes with flexible time correlation structures, and to simulate the arrival times of the processes. The proposed backward construction approach uses the Marshall–Olkin bivariate binomial distribution for the conditional law and some well-known families of bivariate copulas for the joint success probability in lieu of the typical conditional independence assumption. The resulting bivariate Poisson process can exhibit various time correlation structures which are commonly observed in real data. 相似文献
50.
The first-order product autoregressive (PAR(1)) model introduced by McKenzie in 1982 did not attract the attention of practitioners due to the unavailability of a proper estimation method. This article proposes an estimating function (EF) method to fill the gap. In particular, we suggest an optimal combination of linear and quadratic EFs to overcome the problem of parameter identification. The procedure is applied to Weibull and Gamma PAR(1) models. Simulation and data analysis show that the proposed method performs better than the existing methods. 相似文献